Abstract:

The invention relates to an aqueous silicone dispersion, containing one or
more polyorganosiloxanes (POSs) intended to be crosslinked or having been
crosslinked by elimination of water or alcohol, according to a
polycondensation mechanism. The present invention also relates to methods
for preparing aqueous silicone emulsions and dispersions.

Claims:

1. An aqueous silicone dispersion comprising:a) at least one
polyorganosiloxane resin (A) comprising condensable hydroxyl substituents
present in an amount of at least 0.05% by weight;b) at least one
epoxy-functionalized polyorganosiloxane (B);c) at least one water-soluble
hydroxylated alkylaminosilane (C) present in its monomeric form of
general formula (I) and/or in a condensed oligomeric type form:
##STR00008## in which formula:--R1 is an aminoalkyl radical having 1
to 6 carbon atoms or a group of general formula:
H2N--(CH2)xR2--(CH2)z--; with R2
representing O, S, --NH-- or NH--CH2--CH2--NH-- and x≧2,
z≧2;d) at least one surfactant (S);e) optionally at least one
biocide (D);f) water; andg) optionally an effective amount of a
polycondensation catalyst;wherein said aqueous silicone dispersion does
not contain a silane having hydrolyzable functional groups of alkoxy --OR
type with R being a C1-C20 aliphatic hydrocarbon group.

2. The aqueous silicone dispersion as claimed in claim 1, comprising:a) at
least one polyorganosiloxane resin (A) comprising condensable hydroxyl
substituents present in an amount of at least 0.05% by weight;b) at least
one epoxy-functionalized polyorganosiloxane (B);c) at least one
water-soluble hydroxylated alkylaminosilane (C) present in its monomeric
form of general formula (I) and/or in a condensed oligomeric type form:
##STR00009## in which formula:--R1 is an aminoalkyl radical having 1
to 6 carbon atoms or a group of general formula:
H2N--(CH2)xR2--(CH2)z--; with R2
representing O, S, --NH-- or NH--CH2--CH2--NH-- and x≧2,
z≧2;d) at least one surfactant (S);e) optionally at least one
biocide (D); andf) water;wherein said aqueous silicone dispersion does
not contain a silane having hydrolyzable functional groups of alkoxy --OR
type with R being a C1-C20 aliphatic hydrocarbon group.

3. The aqueous silicone dispersion as claimed in claim 1 wherein the
aqueous dispersion is in the form of an oil-in-water emulsion.

4. The aqueous silicone dispersion as claimed in claim 1 wherein the
water-soluble hydroxylated alkylaminosilane (C) is present up to 15% by
weight relative to the total weight of the dispersion, preferably present
up to 10% and even more preferably between 0.5 and 7% by weight.

5. The aqueous silicone dispersion as claimed in claim 1 wherein the
epoxy-functionalized polyorganosiloxane (B) comprises at least one
epoxy-functional radical Y, linked to the silicon via a divalent radical
containing from 2 to 20 carbon atoms and possibly containing at least one
heteroatom, preferably oxygen, bearing at least one epoxy unit, Y
preferably being chosen from the following radicals: ##STR00010##

6. The aqueous silicone dispersion as claimed in claim 1 wherein the
epoxy-functionalized polyorganosiloxane (B) is comprised of one or more
units of formula (V) or is comprised of one or more units of formula (V)
and is terminated by one or more units of formula (VI): ##STR00011## in
which:the R1 symbols are the same or different and represent:a
linear or branched alkyl radical containing 1 to 8 carbon atoms, the
alkyl radicals preferably being methyl, ethyl, propyl and octyl;an
optionally substituted cycloalkyl radical containing between 5 and 8
cyclic carbon atoms;an aryl radical containing between 6 and 12 carbon
atoms which may be substituted, preferably a phenyl or dichlorophenyl
radical; oran arylkyl part having an alkyl part containing between 5 and
14 carbon atoms and an aryl part containing between 6 and 12 carbon
atoms, optionally substituted on the aryl part by halogens, alkyl groups
and/or alkoxy groups containing 1 to 3 carbon atoms; andthe Y' symbols
are the same or different and represent:the group R1; oran
epoxy-functional group, linked to the silicon of the polyorganosiloxane
via a divalent radical containing from 2 to 20 carbon atoms and which may
contain at least one heteroatom, preferably oxygen; andat least one of
the Y' symbols represents an epoxy-functional group.

7. The aqueous silicone dispersion as claimed in claim 5, wherein the
epoxy-functional groups of the epoxy-functionalized polyorganosiloxane
(B) are chosen from the following groups: ##STR00012##

8. The aqueous silicone dispersion as claimed in claim 1, wherein the
polyorganosiloxane resin (A) comprises, before emulsification:condensable
hydroxyl substituents present in an amount of at least 0.05% by weight;
andD, T and optionally M and/or Q siloxyl units, the T siloxyl units
being present in a molar % between 50 and 85% and preferably between 55
and 80%.

9. The aqueous silicone dispersion as claimed in claim 8, in which the
polyorganosiloxane resin (A) is a liquid polyorganosiloxane resin of
T(OH), DT(OH), DQ(OH), DT(OH), MQ(OH), MDT(OH), MDQ(OH) type or mixtures
thereof, and preferably MDT(OH), DT(OH) or mixtures thereof.

10. A method of preparing an aqueous silicone dispersion, comprising:a)
preparinga premix I comprising at least one polyorganosiloxane resin (A)
as claimed in claim 1 and a premix II comprising at least one
epoxy-functionalized polyorganosiloxane (B) as claimed in claim 1 ora
premix III comprising at least one polyorganosiloxane resin (A) as
claimed in claim 1 and at least one epoxy-functionalized
polyorganosiloxane (B) as claimed in one of claim 1;b) emulsifying with
water and in the presence of at least one surfactant (S):premix I and II
obtained in step a); orpremix III obtained in step a); andc) mixing:the
emulsion obtained in step b) with at least one water-soluble hydroxylated
alkylaminosilane (C) as claimed in claim 1; andd) optionally curing the
dispersion of step c) so that crosslinking in the emulsion occurs.

11. An aqueous formulation, comprising:an aqueous silicone dispersion as
claimed in claim 1, said silicone dispersion present in an amount up to
150% by weight relative to the total weight of one or more organic
dispersions;a siliceous or nonsiliceous filler, selected from the group
consisting of: precipitated silica, unprecipitated silica, colloidal or
powdered silica, carbonates, talc, TiO2 and mixtures thereof; andat
least one of the compounds listed below:one or more organic dispersions
selected from the group consisting of (co)polymers of styrene and/or
(meth)acrylic acid or a combination thereof;one or more thickeners
selected from the group consisting of acrylic cellulose thickeners,
polyurethanes, natural gums and mixtures thereof;one or more coalescents,
selected from the group consisting of organic solvents glycols, aliphatic
petroleum cuts and mixtures thereof;one or more wetting agents or
dispersants selected from the group consisting of phosphates,
polyacrylics and a combination thereof;one or more tension agents;one or
more neutralizing agents;one or more biocides;one or more diluents;one or
more plasticizers, selected from non-reactive silicone oils;one or more
antifoaming agents; andone or more pigments or dyes.

12. A paint comprising the aqueous silicone dispersion as claimed in claim
1.

15. A paint comprising the aqueous silicone formulation as claimed in
claim 11.

Description:

[0001]The present invention relates to novel coating compositions,
especially exterior and interior paint compositions. These compositions
may be used in various applications such as water-based paint, casting
products, lazure paints, impregnations, semi-thick coating (STC) or
paints for facades.

[0002]The prior art does not indicate any coating composition that is
capable of being correctly and adequately crosslinked by condensation,
into an elastomer or a crosslinked product, which gives the final
application, for example in the form of paint, an increased wet scrub
resistance (WSR), a beading effect and a water impermeability that are
satisfactory.

[0003]One of the main objects of the present invention is therefore to
provide a novel aqueous silicone coating dispersion giving the final
application an effective waterproofing, that is to say an increased wet
scrub resistance (WSR), a water impermeability, a water vapor
permeability and a beading effect which are satisfactory.

[0004]More specifically, the invention relates to an aqueous silicone
dispersion, containing one or more polyorganosiloxanes (POSs) intended to
be crosslinked or having been crosslinked by elimination of water or
alcohol, according to the polycondensation mechanism taking place,
advantageously, at ambient temperature.

[0005]The present invention also relates to one method amongst others for
preparing aqueous silicone emulsions and dispersions, especially of the
type of those according to the invention.

[0006]Market demand for formulations of the type mentioned above for
environmentally friendly products, which are nontoxic or have low
toxicity (especially containing no volatile organic solvent) and are
convenient and easy to use (e.g. easy washing of tools) has encouraged
producers to develop aqueous dispersions/emulsions that advantageously
can replace solutions and dispersions of organic polymer binders and/or
of silicones in solvents or volatile organic compounds (VOCs).

[0007]Thus, aqueous silicone emulsions have appeared that are intended to
be used as raw materials in the manufacture of paints, STCs or mastics,
and containing one or more silicone oils that can be crosslinked into
elastomers by condensation. The aim of such emulsions is to completely or
partly substitute the organic polymer binders conventionally employed to
date, especially in paints.

[0008]The technical difficulties encountered in the production of these
aqueous silicone emulsions are numerous. It is possible to distinguish
among them a first category, common to all the intended final
applications, and a second category more specific to paints and STCs.

[0009]Regarding the first category, mention should firstly be made of the
storage stability of these oil-in-water (O/W) emulsions. It is clear that
an undesirable phase change of the aqueous silicone emulsion is
completely unacceptable in the applications.

[0010]It is also necessary to pay great attention to safety and toxicity
problems. This is because, even if these are relatively minor owing to
the use of water as a dispersion medium, the fact remains that harmful
products (VOCs) may be generated in situ by hydrolysis. Furthermore, the
curing time of the silicones of the emulsion must not be too long after
application. In addition, the crosslinked product or elastomer which
forms must have suitable mechanical properties (hardness, elasticity,
abrasion resistance) adapted to the application in question.

[0011]It goes without saying that the aqueous silicone emulsion or the
products prepared from this must be easy to use.

[0012]Finally, it is important, regardless of the intended use, that the
material obtained after application (film, coating, seal, filler) adheres
perfectly to the support onto which it is applied.

[0013]Regarding the second category of difficulties specific to paints and
STCs, it must be stressed that the stability of the paint emulsions is
even more crucial.

[0014]Furthermore, a paint must be easy to apply in the form of a film by
known means: by brush, roller, spraying, immersion, etc.

[0015]In addition, it is vital that the paints and also the polymer
binders that they contain, in particular the silicones, crosslink
correctly so as to produce a hard elastomer film. In other words, this
film must not be tacky, so as to prevent dust from sticking to it.
Imperfect curing of the paint film also has the deleterious repercussion
of reducing its durability and its resistance to external environmental
or biological attack.

[0016]There is also a demand for paints to be impermeable to water coming
from outside and permeable to water vapor of internal origin.

[0024]In more concrete terms, the novel aqueous silicone dispersion, that
can be used especially in the formulation of paints, developed and being
the subject of the present invention, is mainly composed of: [0025]a)
at least one polyorganosiloxane resin (A) comprising condensable hydroxyl
substituents present in an amount of at least 0.05% by weight; [0026]b)
at least one epoxy-functionalized polyorganosiloxane (B); [0027]c) at
least one water-soluble hydroxylated alkylaminosilane (C) present in its
monomeric form of general formula (I) and/or in a condensed oligomeric
type form:

##STR00001##

[0028]in which formula: [0029]--R1 is an aminoalkyl radical having 1
to 6 carbon atoms or a group of general formula:
H2N--(CH2)xR2--(CH2)z--; with R2
representing O, S, --NH-- or NH--CH2--CH2--NH-- and x≧2,
z≧2; [0030]d) at least one surfactant (S); [0031]e) optionally at
least one biocide (D); [0032]f) water; and [0033]g) optionally an
effective amount of a polycondensation catalyst;said aqueous silicone
dispersion not containing any silane having hydrolyzable functional
groups of alkoxy --OR type with R being a C1-C20 aliphatic
hydrocarbon group.

[0034]The catalyst is preferably a catalytic tin compound, generally an
organotin salt, preferably introduced in the form of an aqueous emulsion.
The organotin salts that can be used are described, in particular, in the
work by Noll, Chemistry and Technology of Silicones, Academic Press
(1968), page 337.

[0035]It is also possible to use, as a catalytic tin compound, either
distannoxanes, or polyorganostannoxanes, or the reaction product of a tin
salt, in particular of a tin dicarboxylate with ethyl polysilicate, as
described in U.S. Pat. No. 3,862,919.

[0036]The reaction product of an alkyl silicate or of an alkyl
trialkoxysilane with dibutyltin diacetate, as described in the Belgian
Patent BE-A-842 305, may also be suitable.

[0037]According to another possibility, a tin II salt can be used, such as
SnCl2 or stannous octoate.

[0039]According to one particularly advantageous mode, the aqueous
silicone dispersion according to the invention does not have a
polycondensation catalyst and is mainly composed of: [0040]a) at least
one polyorganosiloxane resin (A) comprising condensable hydroxyl
substituents present in an amount of at least 0.05% by weight; [0041]b)
at least one epoxy-functionalized polyorganosiloxane (B); [0042]c) at
least one water-soluble hydroxylated alkylaminosilane (C) present in its
monomeric form of general formula (I) and/or in a condensed oligomeric
type form:

##STR00002##

[0043]in which formula: [0044]--R1 is an aminoalkyl radical having 1
to 6 carbon atoms or a group of general formula:
H2N--(CH2)xR2--(CH2)z--; with R2
representing O, S, --NH-- or NH--CH2--CH2--NH-- and x≧2,
z≧2; [0045]d) at least one surfactant (S); [0046]e) optionally at
least one biocide (D); and [0047]f) water;said aqueous silicone
dispersion not containing any silane having hydrolyzable functional
groups of alkoxy --OR type with R being a C1-C20 aliphatic
hydrocarbon group.

[0048]According to one preferred mode of the invention, the aqueous
dispersion is in the form of an oil-in-water emulsion.

[0049]The problem of improving the mechanical and rheological
characteristics of the paints containing this type of emulsions has been
solved by the Inventors, who did very well to understand that the
solution occurred by the selection of a hydroxylated and water-soluble
aminosilane not having functional groups alkoxylated by organic alkyl
radicals, combined with a polyorganosiloxane resin having hydroxyl
functional groups and with an epoxy-functionalized polyorganosiloxane.

[0050]Contrary to all expectations, it appears that this dispersion is
durably stable and that it satisfies the assigned objectives of improving
the WSR, of ease of preparation and of use, of selective barrier to
exchanges of water in liquid form or vapor form, of safety/nontoxicity
and of improving the beading effect of the paint based on this
dispersion.

[0051]Moreover, it is particularly surprising to notice that after
curing/crosslinking the dispersion is still film forming. Indeed, not
withstanding their crosslinked state and their increased molecular
weight, it is observed that as a film is formed, that the droplets of
resin (A) coalesce and that the dispersion dries.

[0052]Crosslinking in an emulsion--a feature of the invention--makes it
possible to increase, in situ, the average molecular weight of the resin
(A) and its viscosity. Before its crosslinking, the hydroxylated resin
(A) has a sufficiently low weight-average molecular weight Mw and
therefore, in fact, a sufficiently low viscosity in order to be able to
be emulsified. It is not necessary to first dilute this resin in a
solvent in order to be able to emulsify it according to conventional
procedures.

[0053]Consequently, this dispersion according to the invention comprises,
after crosslinking, a silicone crosslinked product or elastomer that has
improved mechanical properties (especially abrasion resistance), without
using toxic and dangerous solvents.

[0054]The constituents (A), (B), (C), (S) and (D) of the dispersion are
defined in the present text through their initial chemical structure,
that is to say the structure that characterizes them before
emulsification. This is because, from the moment that they are in an
aqueous medium, they are converted by hydrolysis/condensation and their
structure then becomes difficult to define.

[0055]The main constituent of the dispersion on the basis of weight is the
polyorganosiloxane resin (A). The hydroxyl groups of this resin are
preferentially borne by the T units, but a hydroxyl substitution of the M
and/or D and/or optionally Q units is not excluded. The level of
hydroxylation is expressed in % by weight. According to this mode of
expression, the minimum hydroxylation is, preferably, equal to 0.05%. In
practice, it is greater than or equal to 0.3% and more preferably still
between 0.5% and 3%.

[0056]In any case, it is advisable that this level of hydroxylation is
sufficient to guarantee correct crosslinking that conforms to the
expected level.

[0057]It is recalled that in the terminology of silicone chemistry, the
siloxane units M, D, T and Q are defined as follows:

##STR00003##

[0058]The resins that are more particularly chosen are those of the type
T(OH), DT(OH), DQ(OH), DT(OH), MQ(OH), MDT(OH), MDQ(OH) or mixtures
thereof. In these resins, each OH group is borne by a silicon atom
belonging to a D, T or Q unit.

[0060]Preferably, the polyorganosiloxane resin (A) comprises, before
emulsification: [0061]condensable hydroxyl substituents present in an
amount of at least 0.05% by weight; and [0062]D, T and optionally M
and/or Q siloxyl units, the T siloxyl units being present in a molar %
between 50 and 85% and preferably between 55 and 80%.

[0064]All the viscosities in question in the present text correspond to an
order of dynamic viscosity at 25° C. said to be "Newtonian", that
is to say the dynamic viscosity is measured, in a manner known per se, at
a low enough shear rate so that the viscosity measured is independent of
the shear rate.

[0065]According to one preferred variant of the invention, the
water-soluble hydroxylated alkylaminosilane (C) is
aminopropyltrihydroxysilane.

[0066]According to one preferred mode of the invention, the water-soluble
hydroxylated alkylaminosilane (C) is present up to 15% by weight relative
to the total weight of the dispersion, preferably present up to 10% and
even more preferably between 0.5 and 7% by weight.

[0067]The epoxy-functionalized polyorganosiloxane (B) of the aqueous
silicone dispersion according to the invention comprises at least one
epoxy-functional radical Y, linked to the silicon via a divalent radical
containing from 2 to 20 carbon atoms and possibly containing at least one
heteroatom, preferably oxygen, bearing at least one epoxy unit, Y
preferably being chosen from the following radicals:

##STR00004##

[0068]According to one preferred mode of the invention, the
epoxy-functionalized polyorganosiloxane (B) is composed of units of
formula (V) and terminated by units of formula (VI) and/or composed of
units of formula (V) represented below:

##STR00005##

[0069]in which: [0070]the R1 symbols are the same or different and
represent: [0071]a linear or branched alkyl radical containing 1 to 8
carbon atoms, the alkyl radicals preferably being methyl, ethyl propyl
and octyl; [0072]an optionally substituted cycloalkyl radical containing
between 5 and 8 cyclic carbon atoms; [0073]an aryl radical containing
between 6 and 12 carbon atoms which may be substituted, preferably a
phenyl or dichlorophenyl radical; [0074]an arylalkyl part having an alkyl
part containing between 5 and 14 carbon atoms and an aryl part containing
between 6 and 12 carbon atoms, optionally substituted on the aryl part by
halogens, alkyl groups and/or alkoxy groups containing 1 to 3 carbon
atoms; [0075]the Y' symbols are the same or different and represent:
[0076]the group R1; and/or [0077]an epoxy-functional group, linked
to the silicon of the polyorganosiloxane via a divalent radical
containing from 2 to 20 carbon atoms and which may contain at least one
heteroatom, preferably oxygen; and [0078]at least one of the Y' symbols
representing an epoxy-functional group.

[0079]According to one preferred mode of the invention, the
organofunctional groups Y' of the epoxy type are chosen from the
following formulae:

##STR00006##

[0080]The epoxy-functionalized polyorganosiloxane (B) may be either linear
or cyclic.

[0081]When they are cyclic polyorganosiloxanes, these are composed of
units (II) which may be, for example, of the dialkylsiloxy or
alkylarylsiloxy type. These cyclic polyorganosiloxanes have a viscosity
of around 1 to 5000 mPas.

[0082]The production of such functionalized polyorganosiloxanes is
perfectly within the reach of a person skilled in the art of silicone
chemistry.

[0083]When a surfactant (S) is used in the dispersion according to the
invention, it is preferably a nonionic surfactant.

[0084]In the context of the present invention, anionic surfactants may
optionally be used. By way of example, mention may be made of the alkali
metal salts of sulfonic or alkylsulfuric aromatic hydrocarbon-based acids
and the preferred nonionic surfactants are polyoxyethylenated
alkylphenols or polyoxyethylenated fatty alcohols.

[0085]The amount of surfactant that can be used is that commonly employed
for emulsification as described, in particular, in U.S. Pat. No.
2,891,920.

[0087]In practice, the dispersion according to the invention comprises
from 30 to 90%, preferably from 30 to 60% by weight of water per 70 to
10%, preferably 70 to 40%, by weight of nonaqueous phase.

[0088]A second subject of the invention relates to a method of preparing
an aqueous silicone dispersion, that can be used especially in the
formulation of paints, characterized in that it comprises the following
essential, successive or non-successive steps:

a) preparation: [0089]of a premix I comprising at least one
polyorganosiloxane resin (A) as defined above, and a premix II comprising
at least one epoxy-functionalized polyorganosiloxane (B) as defined
above; or [0090]a premix III comprising at least one polyorganosiloxane
resin (A) as defined above and at least one epoxy-functionalized
polyorganosiloxane (B) as defined above;b) emulsification with water and
in the presence of at least one surfactant (S): [0091]of each premix I
and II obtained in step a); or [0092]of the premix III; andc) mixing:
[0093]the emulsions obtained in step b) derived from the premixes I and
II with at least one water-soluble hydroxylated alkylaminosilane (C) as
defined above; or [0094]the emulsion obtained in step b) derived from the
premix III with at least one water-soluble hydroxylated alkylaminosilane
(C) as defined above; andd) optional curing of the dispersion derived
from step c) so that crosslinking by condensation and in an emulsion of
the resin takes place within the droplets of the dispersed silicone
phase, in order to obtain a dispersion in the end.

[0095]A third subject of the invention relates to an aqueous formulation,
which can be used especially in the formulation of paints, comprising:
[0096]an aqueous silicone dispersion as defined above, or resulting from
the preparation method as defined above, said silicone dispersion being
preferably present up to 150% by weight relative to the total weight of
one or some of the organic dispersions (binder(s)) and even more
preferably between 40 and 100% by weight; [0097]a siliceous or
nonsiliceous filler, preferably chosen from the following products:
precipitated or unprecipitated silica, colloidal or powdered silica,
carbonates, talc, TiO2 and mixtures thereof; and at least one of the
compounds listed below: [0098]one or more organic dispersions (binders),
preferably chosen from those comprising (co)polymers of styrene and/or
(meth)acrylic acid; [0099]one or more thickeners chosen, preferably, from
acrylic cellulose thickeners, polyurethanes, natural gums and mixtures
thereof; [0100]one or more coalescents chosen, preferably, from organic
solvents and more preferably still from glycols and/or aliphatic
petroleum cuts; [0101]one or more wetting agents or dispersants
preferably chosen from phosphates and/or polyacrylics; [0102]one or more
tension agents; [0103]one or more neutralizing agents; [0104]one or more
biocides; [0105]one or more diluents; [0106]one or more plasticizers,
preferably chosen from non-reactive silicone oils; [0107]one or more
antifoaming agents; and [0108]one or more pigments or dyes (which are
organic or mineral).

[0109]The final subject of the invention relates to a paint, characterized
in that it comprises: [0110]the aqueous silicone dispersion according
to the invention; [0111]the aqueous silicone dispersion obtained by
implementing the method according to the invention; or [0112]the aqueous
formulation according to the invention.

[0113]The paint according to the invention may be applied, for example, to
facades in accordance with the customary techniques. By way of example,
it may be applied to the surfaces by any suitable means such as by
brushing, spraying, etc. The surfaces on which the coating composition
according to the invention can be applied are of diverse nature: for
example, metal such as aluminum, wood, cement, brick, with or without
prior coating with an adhesion primer.

[0114]The following examples and tests are given by way of illustration.
They make it possible especially to better understand the invention and
to highlight all its advantages and to anticipate some embodiment
variants.

[0117]water-soluble hydroxylated alkylaminosilane (C): aqueous hydroxylate
of γ-aminopropyltriethoxysilane with 20% of active material, from
which the alcohol has been removed by stripping (OSI commercial product
of type VS142); [0118]silane with alkoxy group:
OTES=octyltriethoxysilane; [0119]surfactants (S): an ethoxylated (8
ethoxy units) fatty alcohol (chain of 13 carbons) sold under the
tradename ROX® by Rhodia Chimie; [0120]Catalyzing emulsion (Cat):
emulsion of dioctyltin dilaurate with 35% of active tin material produced
with a polyvinyl alcohol type surfactant, in this case the one sold under
the trademark RHODOVIOL®; and [0121]OTES=octyltriethoxysilane.

B) Methodology for Preparing Emulsions

[0122]Several protocols for preparing dispersions can be envisaged.
Without this being limiting, the protocol used in the present examples
consists in: [0123]1--mixing the water and the surfactant or
surfactants (S); [0124]2--incorporating the polyorganosiloxane resin(s)
(A) and the epoxy-functionalized polyorganosiloxane (B) into this water
mixture, this incorporation being carried out with stirring so as to
obtain a water-in-oil emulsion; [0125]3--carrying out the inversion of
the water-in-oil (W/O) emulsion obtained in step 2 by blending (MORITZ
blender) in order to eventually obtain an oil-in-water (O/W) emulsion;
and [0126]4--making the subsequent additions by mixing the silane(s).

[0127]One variant consists in mixing two emulsions in step 2, one
containing the polyorganosiloxane resin (A) and the other the
epoxy-functionalized polyorganosiloxane (B). For comparative tests, the
constituents used vary depending on the case.

C) Test of the Wet Scrub Resistance (WSR)

[0128]A paint applied inside or outside must be able to be cleaned easily
without being degraded. For this type of product, the binding power of
the polymer, that is to say its ability to ensure the cohesion of the
assembly, is a determining factor.

[0129]A means of quantifying this property consists in evaluating the wet
scrub resistance of a paint.

DEFINITIONS OF THE WET SCRUB RESISTANCE

[0130]According to the standard ISO 11998=Loss of thickness of a paint
film after a defined scrub cycle and carried out using a standard
apparatus.

Principle

[0131]Evaluation of the ability of a paint film of defined thickness to
resist the abrasive action exerted by the back and forth movement of a
brush or of an abrasive pad in an aqueous medium.

Expression of the Results

[0132]For the standard ISO 11998 [0133]for each test piece, apply the
following formula:

[0133]Δm×106/(39×387×ds)
[0134]where: [0135]Δm is the difference in weight of the
test piece before and after the test; and [0136]ds is the dry
density of the paint. [0137]for each paint, calculate the average and
the standard deviation; [0138]express the result in μm, which
corresponds to a loss of thickness of the paint film. There is a
classification of paints as a function of the loss of thickness and of
the number of scrub cycles:Class 1: <5 μm after 200 cycles, for
paints having a high degree of binder.Class 2: ≧5 μm and <20
μm after 200 cycles, the paint is cleanable.Class 3: ≧20 μm
and <70 μm after 200 cycles, the paint is washable.Class 4: <70
μm after 40 cycles.Class 5: ≧70 μm after 40 cycles.

D) Water Permeability (W24): Standardized Test for Liquid Water Absorption

[0139]This procedure (standard NF EN 1062-3, February 1999) specifies a
method for determining the liquid water permeability of paint products
and similar products, applied to exterior masonry and concrete. This
method can be applied to the paint products and coating systems for
porous supports such as for example: bricks, concrete and render.

Principle

[0140]The coatings for exterior masonry and concrete play an important
part in preventing the penetration of runoff water in the porous mineral
supports. This criterion is evaluated by means of high-porosity mineral
blocks where one of the faces is coated with the coating or the coating
system. The test piece is immersed in water, under set conditions and the
test pieces are weighed at regular time intervals. The liquid water
permeability is determined by the change in mass when the change in mass
is directly proportional to the square root of the time interval.

Expression of the Results

[0141]Determine the increase in the weight of water as a function of the
square root of the time. The slope of the linear part of the curve is the
liquid water transmission coefficient W in kg/m2t1/2 in hours.
To obtain the coefficient W it is necessary to divide the increase in the
weight by the surface area, in m2, or to divide the slope by the
surface area. The surface area will be the surface area not covered by
paraffin. Normally, W is calculated for a period of 24 hours. If the part
of the curve is obtained before 24 hours, the number of hours must be
indicated as an index of W (e.g. W6).

[0142]PVC=pigment volume capacity.

2) Procedure for the Accelerated Water Absorption Test

Procedure

[0143]The water absorption is influenced by compounds that are volatile
and soluble in water. In practice, these compounds may evaporate from the
coating during its exposure to the outside or be washed away by rain, the
coating must undergo an "accelerated" aging before the determination of
its liquid water absorption (two washes instead of the three expected in
the conventional procedure).

Preparation of the Test Pieces

[0144]Apply a 300 μm film of paint (two test pieces for one same
paint) to a sandstone tile. [0145]Leave to dry during the day in an
air-conditioned room. [0146]Place the test pieces, in the evening, in an
oven at 30° C. and left overnight. The next morning, set the oven
at 40° C. and leave the test pieces for 48 hours (2 days).
[0147]Put the test pieces in an air-conditioned room for the morning.
[0148]In the afternoon, paraffin the test pieces using a Leneta chart
placed on the coating. [0149]Conditioning in an air-conditioned room for
a minimum of one day.

Accelerated Aging

[0149][0150]Place the sponges in a tank. Immerse them in demineralized
water up to 0.5 cm below the height of the sponge. Place the test piece
on the water-soaked filter. Leave the system thus for 24 h. [0151]Dry the
test piece with absorbent paper then place it in an oven at 50° C.
for 24 h. [0152]Bring the test piece back into contact with water by
means of the filter/sponge for 24 h. [0153]Dry the test piece with
absorbent paper then place it in an oven at 50° C. for 24 h.
[0154]Store the test pieces in an air-conditioned room for 2 to 3 days.

Determination of the Liquid Water Absorption

[0154][0155]After conditioning in an air-conditioned room, weigh the
coated and aged test piece. Place it on the sponge wetted by means of the
filter. [0156]After 1 h, 2 h, 3 h, 6 h and 24 h weigh the test piece,
whose surface will first be dried with absorbent paper (the test piece is
replaced on the sponge between each weighing).

Expression of the Results

[0157]The increase in the weight of water is a function of the square root
of the time (Δweight=f( {square root over (t)})).

[0158]The slope of the linear part of the curve is W, the liquid water
transmission coefficient in kg/(m2t1/2). In order to obtain the
coefficient W it is necessary to divide the increase in the weight by the
surface area in m2 of the coating or to divide the slope by the
surface area.

[0159]Normally, W is calculated for a period of 24 hours. If the linear
part of the curve is obtained before 24 hours, the number of hours must
be indicated as an index of W (e.g. W6). Plot the water absorption
curve in kg/m2 as a function of {square root over (time)}. A
straight line is obtained. The slope is equal to the transmission
coefficient W. For each coating studied, the average and the standard
deviation of W24 will be calculated and presented.

[0165]The results show that the dispersion according to the invention make
it possible to avoid using a catalyst and an alkoxylated silane (commonly
used in the aqueous silicone formulations for paint). This accordingly
simplifies the formulation and the method of manufacture, which is
particularly profitable from a production cost viewpoint. The dispersions
according to the invention make it possible to obtain W24 values
that allow them to be classed as paints having a low liquid water
permeability.

[0166]In addition, the paints according to the invention have, after
application and drying, an acceptable beading effect for the desired
application.